This invention relates to simple, effective and inexpensive pipe couplings for use in the connection of pipes. The coupling includes a first annular seal that not only acts to clean the pipes during insertion thereof, but also precludes the entry of foreign materials, particularly sand or dirt used as back fill, from entering in between the coupling and the inserted pipes. The coupling also includes a second annular inner seal that prevents leakage between the inserted pipes and coupling while in use.
Heretofore, difficulty has been encountered in the prior art in attempting to seal couplings and pipes to prevent the deleterious effects resulting from entry of sand or dirt or other foreign material between the pipes and coupling, i.e., to prevent leakage into or from between the pipe and coupling, while in use. Many prior art attempts have been made to seal the coupling and the pipe; however, such attempts have been generally limited in that their use-life has been short. For example, taping, gluing, packing and other bonding methods have all resulted in a very short use-life, particularly with pipes subjected to pressures other than atmospheric with respect to the differential pressures in the pipes between the coupling and the pipes. The result being that, in many cases, it has been necessary to periodically, on a short time basis, require either preventive maintenance or maintenance after a leak between the coupling and pipe has been discovered. These prior art methods have also resulted in considerable expense not only from the maintenance standpoint, but also from the break-down standpoint involving, in some cases, the requirement of a shutdown of the entire pipe line. These problems have been shown to be particularly acute with respect to pipes made of ferrous type materials.